Rosa Brooks, a former Pentagon official who is now a Georgetown law professor (and a fellow FP writer), said the lines of warfare and much else are much murkier than they were a few decades ago.

“Is a line of code a weapon?” she asked at the CNAS conference. “Well, it can kill people. It can do real damage.” (Tom: Glock vs. GLOC.)

She said it is crucial to be conscious of the legal framework you impose on a situation, because that can drive decisions. If you think a terrorist act is a criminal act, you will respond to it one way. If you decide it was an act of war, you will act in another way. Being unclear about this can lead to a haziness in strategy. “Because we can lawfully do almost anything, we do almost everything.” And a danger is that the next step is that other nations will imitate that approach.

She also made the point that drones might be better (and more ethical) about killing people than people are. “We have robocars, and it turns out they not only can drive a car as well as a human, they can do it better, because we have limited attention spans.” What, she asked, if drones are less prone to make mistakes?